(1) Field of the Invention
This invention relates to a thermopile for a heat flow meter and a process for manufacturing thereof. More particularly, it relates to a thermopile having good quality, which contains metal segments supported on a substrate, and to a process for manufacturing this thermopile at a high efficiency by utilizing plating and photo-etching techniques.
(2) Description of the Prior Art
A thermometer utilizing a thermoelectromotive force is ordinarily called a "thermoelectric thermometer" and is in common use in various fields. A thermoelectric thermometer is composed of thermocouples which in turn are composed of lines of different metals, such as copper and constantan formed in a closed circuit. In order to measure the temperature, one connection point of the circuit is maintained at 0.degree. C. or room temperature while the other connection point is attached to the material, the temperature of which is to be measured. The temperature difference between the two connection points is measured by detecting a thermoelectromotive force generated by this temperature difference. Various combinations of metals are used for these thermocouples. Good results are obtained when this temperature difference is large. However, when the temperature difference between the two connection points is slight, the thermoelectromotive force generated in these thermocouples is small and it is difficult or even impossible to measure the temperature of the material.
In order to overcome this difficulty in measurement, a thermopile, an apparatus consisting of a number of thermocouples combined so as to multiply electric currents, is utilized. Most conventional thermopiles are prepared by winding metal wires or metal foils on a heat-resistant substrate or embedding metal wires or metal foils in a heat-resistant substrate. However the conventional process for manufacturing such thermopiles is complicated and its productivity is very low. Moreover, the stability in the performances of the products is not satisfactory.